A tear, rip, slit, or crack formed where something has split; also used metaphorically for a rift between people or groups.
シャツに大きな裂け目ができてしまった。
A large tear appeared in my shirt.
地震で道路に裂け目が入った。
The earthquake caused a crack in the road.
長年の信頼関係に裂け目が生じた。
A rift developed in a long-standing relationship of trust.